1. Field of the Invention
The present invention relates in general to an economical scanner in which changing the positions of lenses is performed by way of the movement of an optical module rather than an additional driving mechanism.
2. Description of the Related Art
A scanner provided with two lenses has been published. The resolutions of the two lenses are different so that the user can choose to use one of the lenses. Generally speaking, a lens of high resolution can provide a good scanning quality, but also provides a lower scanning speed and a smaller scanning zone. On the other hand, a lens of low resolution can provide a better scanning speed and a larger scanning zone. However, the scanning quality is poor. In brief, the choice of the lenses depends on the user""s desire for the scanning quality or scanning speed.
The related arts include U.S. Pat. Nos. 5,535,040 and 5,552,939, in both of which a driving mechanism is additionally provided for changing the positions of the lenses for use. It is known that a scanner already has a driving mechanism for driving an optical module to scan documents. However, a scanner of the related art necessarily includes another driving mechanism to change the positions of the lenses for use. That obviously costs more and thus is not economical.
An object of the present invention is to provide an economic scanner which requires only one driving mechanism for both driving an optical module along a scanning path for scanning a document and changing the lenses for use.
The scanner of the present invention has a base, at least one guiding member and an optical module. The base has a changing zone. The guiding member is connected onto the base. The optical module has a movable lens mount, a swing""mechanism rotatably connected to the lens mount, a first lens provided on the lens mount and a second lens also provided on the lens mount. When the optical module moves into the changing zone of the base, the swing mechanism is pushed by the guiding member and then rotates so that the lens mount connected to the swing mechanism begins to move until one of the first or second lensesand provided on the lens mount moves to a predetermined position for use.
It is therefore understood that changing the positions of the first and second lenses is performed by way of the movement of the optical module rather than an additional driving mechanism.